The present invention relates to portable storage devices, and in particular to portable storage devices including a microprocessor.
Portable storage devices are in commercial use for many years to carry data from one computer to another or to store backup data. The simpler devices, such as floppy disks or writable CDs are dumb in the sense that they do not include processing power. The more sophisticated ones, such as portable hard disk drives or portable flash memory disks, do include a microprocessor for controlling the storage management.
When a portable storage device is connected to a computer, the computer takes control over the read/write operation via its operating system. Thus, there is a procedure of “mounting” the portable storage device, in which data exchanged between the device and the computer establishes the storage device as another disk drive, and from this moment on, the computer controls all read/write operations under well-established standards. If the storage device is dumb, for instance with a floppy disk, then the computer manages all physical addressing through file allocation tables (FAT) that are maintained on the storage device. However, when the storage device includes a microprocessor, the addressing made by the computer is actually virtual, since the microprocessor can transform addresses received from the computer to other addresses, for example for wear-leveling of flash memory disks.
A user of a portable storage device may lose it and then face the risk of others reading his files. This may be highly undesirable since such files may contain personal or commercially-confidential information. A commonly-used solution for protecting data is encryption. A file that is considered confidential will be encrypted using a common encryption algorithm such as Data Encryption Standard (DES) or triple-DES using a secret key known only to the user. Thus, an obvious way for protecting data carried on a portable storage device would be encrypting it on the computer and then copying the encrypted version onto the portable device and carrying it securely. When approaching another computer having a compatible decryption software, the user will need to copy the encrypted version onto that computer and key-in the secret key in order to open the file and use it normally.
The method described above will be however inconvenient, since not all visited computers may have the appropriate software, and manual encryption and decryption of individual, selected files is cumbersome.
There is therefore, a need to secure the data stored on portable storage devices independently of a host device, and allow access only when the user has provided an appropriate password or biometric identification data.